OBSERVATION OF NANOSPHERICAL n-SnO2/p-Si HETEROJUNCTION FABRICATED BY ULTRASONIC SPRAY PYROLYSIS TECHNIQUE

Abstract

Thin film of tin oxide ( SnO 2) was prepared on p-type polished silicon wafer by ultrasonic spray pyrolysis technique using SnCl 4 precursor solution to fabricate nanospherical n - SnO 2/ p - Si heterojunction photoelectric device. Deposition of film was achieved at 400°C substrate temperature. The self-made ultrasonic spray pyrolysis system is very cheap and convenient. The microstructural, optical and electrical properties of the SnO 2 film were characterized by XRD, SEM, XPS, UV-VIS spectrophotometer, four point probe and Hall effect measurement, respectively. The SnO 2 film has the nanospherical particles. The electrical properties of heterojunction were investigated by I–V measurement, which reveals that the heterojunction shows strong rectifying behavior under a dark condition. The ideality factor and the saturation current density of this diode are 4.27 and 2.52 × 10-6 A/cm2, respectively. And the values of IF/IR (IF and IR stand for forward and reverse current, respectively) at 5 V is found to be as high as 248. The SnO 2/ p - Si heterojunction device exhibits obvious photovoltaic effect. Under an AM1.5 illumination condition, the open-circuit voltage (V oc ), short-circuit current density (J SC ), fill factor (FF) of the device are 150 mV, 3.9 × 10-3 mA/cm2 and 20.58%, respectively. High photocurrent is obtained under a reverse bias when the crystalline quality of SnO 2 film is good enough to transmit the light into p- Si . Under 6.3 mW/cm2 illumination, when the reverse bias is -5 V, the photocurrent gain is as high as 86.